We just released a Web API Test Sandbox at the ReportingCloud portal. This sandbox can be used to test Web API calls with your account data and your template storage (so not a completely isolated sandbox per definition) that doesn't count against your document quota.
The following screenshot shows the sandbox in action for the merge endpoint:
![Web API Test Sandbox released on ReportingCloud Portal Web API Test Sandbox released on ReportingCloud Portal](https://s1-www.textcontrol.com/application-1.6833.50319/blog/2016/10/07/a/assets/sandbox.webp)
The overview page also lists some sample Web API calls and in the Web API Endpoint Reference, each endpoint description shows a button to launch the test sandbox for that endpoint:
![Web API Test Sandbox released on ReportingCloud Portal Web API Test Sandbox released on ReportingCloud Portal](https://s1-www.textcontrol.com/application-1.6833.50319/blog/2016/10/07/a/assets/docs.webp)
Happy coding!